// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SPDY_SPDY_WRITE_QUEUE_H_
#define NET_SPDY_SPDY_WRITE_QUEUE_H_

#include <deque>
#include <memory>

#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "net/base/net_export.h"
#include "net/base/request_priority.h"
#include "net/spdy/spdy_protocol.h"

namespace net {

class SpdyBuffer;
class SpdyBufferProducer;
class SpdyStream;

// A queue of SpdyBufferProducers to produce frames to write. Ordered
// by priority, and then FIFO.
class NET_EXPORT_PRIVATE SpdyWriteQueue {
public:
    SpdyWriteQueue();
    ~SpdyWriteQueue();

    // Returns whether there is anything in the write queue,
    // i.e. whether the next call to Dequeue will return true.
    bool IsEmpty() const;

    // Enqueues the given frame producer of the given type at the given
    // priority associated with the given stream, which may be NULL if
    // the frame producer is not associated with a stream. If |stream|
    // is non-NULL, its priority must be equal to |priority|, and it
    // must remain non-NULL until the write is dequeued or removed.
    void Enqueue(RequestPriority priority,
        SpdyFrameType frame_type,
        std::unique_ptr<SpdyBufferProducer> frame_producer,
        const base::WeakPtr<SpdyStream>& stream);

    // Dequeues the frame producer with the highest priority that was
    // enqueued the earliest and its associated stream. Returns true and
    // fills in |frame_type|, |frame_producer|, and |stream| if
    // successful -- otherwise, just returns false.
    bool Dequeue(SpdyFrameType* frame_type,
        std::unique_ptr<SpdyBufferProducer>* frame_producer,
        base::WeakPtr<SpdyStream>* stream);

    // Removes all pending writes for the given stream, which must be
    // non-NULL.
    void RemovePendingWritesForStream(const base::WeakPtr<SpdyStream>& stream);

    // Removes all pending writes for streams after |last_good_stream_id|
    // and streams with no stream id.
    void RemovePendingWritesForStreamsAfter(SpdyStreamId last_good_stream_id);

    // Removes all pending writes.
    void Clear();

private:
    // A struct holding a frame producer and its associated stream.
    struct PendingWrite {
        SpdyFrameType frame_type;
        // This has to be a raw pointer since we store this in an STL
        // container.
        SpdyBufferProducer* frame_producer;
        base::WeakPtr<SpdyStream> stream;
        // Whether |stream| was non-NULL when enqueued.
        bool has_stream;

        PendingWrite();
        PendingWrite(SpdyFrameType frame_type,
            SpdyBufferProducer* frame_producer,
            const base::WeakPtr<SpdyStream>& stream);
        PendingWrite(const PendingWrite& other);
        ~PendingWrite();
    };

    bool removing_writes_;

    // The actual write queue, binned by priority.
    std::deque<PendingWrite> queue_[NUM_PRIORITIES];

    DISALLOW_COPY_AND_ASSIGN(SpdyWriteQueue);
};

} // namespace net

#endif // NET_SPDY_SPDY_WRITE_QUEUE_H_
